An RFID tag could change hands many times during its lifetime. In a retail chain, the ownership of the tag is instituted by the supplier who initially owns the tag. In the view of a buyer, the validity of the current tag ownership and the originality of supplier are most important. In typical RFID ownership transfer protocols, the knowledge of the tag's authentication key proves the ownership. However, it is insufficient against an active attacker, since tags are usually lack of tamper-proof protections. Ownership transfer relies on a successful verification of tag's supplier and current ownership. In this paper, we formally define the security model of ownership transfer protocols and propose a secure ownership transfer protocol. In our scheme, current owner provides a new owner with the evidence of transfer and a proof of tag origin. Key management becomes easy in our system, since the one asymmetric verification key of the owner can be used to verify multiple tags that belong to the owner.